Complementary metal oxide semiconductor (CMOS) transistors are building blocks for integrated circuits. A CMOS transistor generally comprises a semiconductor substrate, a channel layer above or within the semiconductor substrate, a gate oxide layer and a gate stack above the channel layer, and source and drain diffusion regions in the surface of the semiconductor substrate. Electrical contacts are made to the gate stack, and to the source and drain diffusion regions of the CMOS transistor. With the advent of high-K dielectric materials as a gate insulating layer in the CMOS process, metal gates may be used in the CMOS devices.
Low-resistance contacts to semiconductor materials are important for the performance and reliability of semiconductor devices. As CMOS transistor dimensions scale down, semiconductor materials, e.g., InGaAs, are used to replace traditional silicon substrates. As such, providing low resistance contacts at metal-semiconductor junctions, e.g., between, among other things, a metal contact and the semiconductor materials of and/or about a source/drain region is an important objective in the design and manufacture of metal-semiconductor structures.